I did finally get the serial decode working, I was confused as I'd assumed that the activation code sent with the link to the firmware was for the decode. It was actually for the 500uV. After I'd confirmed I'd installed the firmware, I was sent a further activation code which enabled the decode.
I've used it on I2C and UART. It seems to work reasonably well despite it being beta. Sometimes doesn't properly decode I2C bytes at certain timebase speeds, by altering the timebase either slower or faster it will properly decode, so I don't think it's due to excessive subsampling. It only decodes what's currently on the screen, and there is no lister/event functionality. The serial trigger functionality seems to be fine so far.
It is useable enough for me to consider this a reasonable option for field use, the serial decode and trigger functionality is pretty much a prerequisite nowadays for my work. The form factor and being battery powered is the icing on the cake.